Manufacture of nitrocellulose smokeless powder



Patented June 9, 1931 ALAN S. HAWKESWORTH, OF WASHINGTON, DISTRICT OF COLUMBIA MAN'Q'FACTURE NITROCELLULOSE SMOKELE SS POWDER I No Drawing.

This invention has for its object, the modification, to suit present working conditions and routine, of the process of such manufac ture set forth in my prior Patent 1,713,505;

granted to me 14th May, 1929.

After the nitration of the cotton fibre, or

cellulose, it must be thoroughly washed in water to eliminate the exceedingly dangerous free nitric acid andfthen must be dried or de-hydrated. In my previous Patent 1,713,505 I accomplished this by employing an excess of my combined dryer, solvent, and stabilizer, mono-nitro-toluene, which excess had then to be eliminated, by centrifuging 15 or some similar method. But in this improvedprocess I am only going to employ the irreducible minimum of around 6% mono-- nitro-toluene so that the Washed and damp nitrocellulose is now de-hydrated by the addition of alcoholin the present customary way. A

And when the nitrocellulose is so dried, and ready for the solvent, I now use only the stated irreducible minimum, of around 6% or so by volume, of mono-nitrotoluene; and add say three or four times as much ether to make the compound excess solvent. To every 100 parts by volume of the nitrocellulose, there are added about 6 or 7 parts by volume of mono-nitro-toluene and say 20 parts by vol ume of ether; or whatever excess may be needed to make a smooth, easily workable colloid or paste, which excess of solvent also ensures the complete dis-solution or solution 7 of the nitrocellulose.

Having so dissolved thoroughly the nitrocellulose and made my desired powder grain patternAmerican, strip, or any other from the soft paste; the completed powder grain is then baked at a very moderate temperature (around blood heat) in the drying oven, and all the superfluous ether solvent evaporated out. Since the mono-mtro-toluene boils at the high temperature of 220.4:

Cent. or 428.7 Fahr. it is absolutely unaffected by the moderate temperature that drives out and evaporates the ether. The non-evaporable mono-nitro-toluene is thus left hermetically sealing each and every molecule of the nitrocellulose in its own water- Application filed June 13,

1930. Serial No. 461,056.

proof and cushioned cell, making an absolutely safe powder that cannot deteriorate from elapsed time, or extreme climatic conditions, and, incidentally, also being incapable the office of a stabilizer, and not merely using it, like other greasy stabilizers, as an after addition and mechanical admixture, after the powder is made whereby no such intimate coating is possible.

But when the mono-mtro-toluene alone 1s used, the necessary excess (ensuring complete solution of the nitrocellulose) is difficult to.

remove, and by this presentuse of acompound solvent, composed of the minimum needed mono-nitro-toluene and the excess solvent of ether, or other easily evaporable solvent, my obtain a paste that, when the desired powder grain is moulded, can be easily and quickly dried and hardened in the drying oven, and drying and hardening, however, absolutely ceases, when allthe ether is drivenofflandthe non-evaporable mono-nitro-toluene left behind to do its preserving work, 'a state'that will continue unaltered, instead of the drying out and hardening still continuing while in storage, to the danger point as with the present smokeless powder; where the ether solvent is employed alone in which some greasy stabilizer is added after the powder is made.

I claim:

The process of making nitrocellulose smokeless powder which comprises, the addition as a solvent and stabilizer of mono-nitrotoluene of around at least 6% by volume of the finished powder grain as the irreducible minimum, needed to completely coat each molecule of the nitrocellulose, together with the addition of an easily evaporable solvent suflicient to make a compound solvent that will completely dissolve the nitrocellulose into a smooth paste, and evenly distribute the mono-nitro-toluene, then moulding the said paste into the desired powder grain,

and driving ofi the excess evaporable solvent from the finished powder grain by means of moderate heat, thereby leaving the non-evap orable mono-nitro-toluenecoating over each and every one of the nitrocellulose molecules.

' ALAN S. HAWKESWORTH. 

